Cellulose ethers (i.e., methylcellulose and sodium carboxymethylcellulose) have multiple uses in paper conservation. This investigation attempts to provide additional information on three cellulose ethers Methocel A4M (methylcellulose), Hercules Cellulose Gum CMC 7HSP (sodium carboxymethylcellulose), Cellofas B3500 (sodium carboxymethylcellulose) -- by accelerated aging in a humid oven in the absence of light. Information is given on the chemical and physical properties of each; it is concluded that cellulose ethers do add strength to paper without dramatically lowering pH or changing the paper's color. A mixture of Methocel A and CMC 7HSP provides a better size and/or adhesive than either alone. See also 21-1334 for reference to entire proceedings. -- AATA